The present invention relates to a method of and a device for measuring an antioxidation capability of a liquid sample.
More particularly, the present invention relates to a method of and a device for measuring a total antioxidation capability of living systems, particularly of blood, and to a method of and device for measuring an amount of a compound having an antioxidation capability, particularly of a polyphenol compound.
Since it was found that activated oxygen indiscriminately oxidizes various cell components to yield different types of oxygenated damage, awareness of the importance of antioxidation potencies in the living system and compounds having a certain antioxidative capability has increased in fields related to health maintenance.
The antioxidation potency intrinsic in living systems has hitherto been measured by direct quantitative determination of the individual antioxidants present in tissues and blood. Antioxidants found within the living systems include superoxide dismutase (SOD), catalase, glutathione peroxidase, vitamin E, ascorbic acid (vitamin C), billirubin, .beta.-carotene, etc. Accordingly, the antioxidation potency of the living system can be determined by examining the prevailing quantity or activity of the respective components existing in living tissues such as blood, etc.
Although each of the antioxidation potencies of individual substances possessing antioxidative activities may be measured by the above-mentioned method, the total antioxidation potency actually found in an individual living system as a whole remains unestablished. This is because the antioxidation mechanism prevailing within the living system is so complicated that synergistic effects contributed by a combination of a plurality of antioxidants sometimes arise. It is therefore difficult to monitor the actual degree of antioxidative effects elicited by each of the antioxidants concerned. In short, even if the respective activities and prevailing quantities of the antioxidants were individually determined and subsequently summed up, the total antioxidation potency actually found in the living system would still remain unknown.
While it is important to know the total antioxidation potency actually found in a living system as mentioned above, it is also important to quantitatively determine the antioxidation capability of individual compounds.
Of the many compounds having antioxidation potency, polyphenol compounds have especially been focused upon. Polyphenol compounds are compounds having a plurality of phenolic hydroxyl groups, such as tannins (catechins, gallic acid, caffeic acid derivatives, etc.), flavonoids (flavones, flavonols, antocyanins, etc.), lignan, lignin, coumarins, etc.
Among the above mentioned polyphenol compounds, particular attention has been focused on (-) -epigallocatechin-3-gallate (hereinafter also referred to as EGCg), which is contained mainly in green tea, as this compound elicits antimutagenecity and anticarcinogenicity in addition to its antioxidation capability.
However, a method of measuring the polyphenol compounds in a specific and high-sensitive way has not yet been established.
Hitherto, detection of isolated components by high-speed liquid chromatography using detectors such as ECD (electrochemical detector), UV (ultraviolet absorption detector), etc. has been employed in the analysis of polyphenol compound contained, for example, in food and living body samples. With these conventional methods, it is not possible to specifically detect only the polyphenol compound. One of the reasons being the overlapping of peaks of several unknown compounds with that of the target compound obtained by the high performance liquid chromatography. Therefore, a method that can detect the polyphenol compound in a specific and high-sensitive way is required.